linux-kernel - [PATCH 3.16 072/294] powerpc/boot: Fix 64-bit boot wrapper build with non-biarch compiler

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Date:   Mon, 06 Nov 2017 23:03:02 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Cyril Bur" <cyrilbur@...il.com>,
        "Michael Ellerman" <mpe@...erman.id.au>
Subject: [PATCH 3.16 072/294] powerpc/boot: Fix 64-bit boot wrapper build
 with non-biarch compiler

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Ellerman <mpe@...erman.id.au>

commit 65c5ec11c25eff6ba6e9b1cbfff014875fddd1e0 upstream.

Historically the boot wrapper was always built 32-bit big endian, even
for 64-bit kernels. That was because old firmwares didn't necessarily
support booting a 64-bit image. Because of that arch/powerpc/boot/Makefile
uses CROSS32CC for compilation.

However when we added 64-bit little endian support, we also added
support for building the boot wrapper 64-bit. However we kept using
CROSS32CC, because in most cases it is just CC and everything works.

However if the user doesn't specify CROSS32_COMPILE (which no one ever
does AFAIK), and CC is *not* biarch (32/64-bit capable), then CROSS32CC
becomes just "gcc". On native systems that is probably OK, but if we're
cross building it definitely isn't, leading to eg:

  gcc ... -m64 -mlittle-endian -mabi=elfv2 ... arch/powerpc/boot/cpm-serial.c
  gcc: error: unrecognized argument in option ‘-mabi=elfv2’
  gcc: error: unrecognized command line option ‘-mlittle-endian’
  make: *** [zImage] Error 2

To fix it, stop using CROSS32CC, because we may or may not be building
32-bit. Instead setup a BOOTCC, which defaults to CC, and only use
CROSS32_COMPILE if it's set and we're building for 32-bit.

Fixes: 147c05168fc8 ("powerpc/boot: Add support for 64bit little endian wrapper")
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Reviewed-by: Cyril Bur <cyrilbur@...il.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
--- a/arch/powerpc/boot/Makefile
+++ b/arch/powerpc/boot/Makefile
@@ -21,11 +21,19 @@ all: $(obj)/zImage

 BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
 		 -fno-strict-aliasing -Os -msoft-float -pipe \
-		 -fomit-frame-pointer -fno-builtin -fPIC -nostdinc \
-		 -isystem $(shell $(CROSS32CC) -print-file-name=include)
+		 -fomit-frame-pointer -fno-builtin -fPIC -nostdinc
+BOOTCC := $(CC)
 ifdef CONFIG_PPC64_BOOT_WRAPPER
 BOOTCFLAGS	+= -m64
+else
+BOOTCFLAGS	+= -m32
+ifdef CROSS32_COMPILE
+    BOOTCC := $(CROSS32_COMPILE)gcc
+endif
 endif
+
+BOOTCFLAGS	+= -isystem $(shell $(BOOTCC) -print-file-name=include)
+
 ifdef CONFIG_CPU_BIG_ENDIAN
 BOOTCFLAGS	+= -mbig-endian
 else
@@ -165,10 +173,10 @@ clean-files := $(zlib) $(zlibheader) $(z
 		empty.c zImage.coff.lds zImage.ps3.lds zImage.lds

 quiet_cmd_bootcc = BOOTCC  $@
-      cmd_bootcc = $(CROSS32CC) -Wp,-MD,$(depfile) $(BOOTCFLAGS) -c -o $@ $<
+      cmd_bootcc = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTCFLAGS) -c -o $@ $<

 quiet_cmd_bootas = BOOTAS  $@
-      cmd_bootas = $(CROSS32CC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<
+      cmd_bootas = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<

 quiet_cmd_bootar = BOOTAR  $@
       cmd_bootar = $(CROSS32AR) -cr$(KBUILD_ARFLAGS) $@...$$ $(filter-out FORCE,$^); mv $@...$$ $@